Fluid ejection devices eject drops on demand. For example, fluid ejection devices are present in three-dimensional (3D) printers, two-dimensional (2D) printers, such as inkjet printers, and other high precision digital dispensing devices, such as digital titration devices.
Inkjet printers print images by ejecting ink drops through a plurality of nozzles onto a print medium, such as paper. Nozzles are typically arranged along a printhead in one or more arrays, such that properly sequenced ejection of ink drops from the nozzles causes characters or other images to be printed on the print medium as the printhead and the print medium move relative to each other. Thermal inkjet printheads eject drops from nozzles by passing electrical current through heating elements that generate heat and vaporize small portions of fluid within firing chambers. Piezoelectric inkjet printheads use piezoelectric material actuators to generate pressure pulses that force ink drops out of nozzles.